From: Liu, Yi L yi.l.liu@intel.com Sent: Monday, December 11, 2023 4:08 PM
On 2023/12/7 16:47, Tian, Kevin wrote:
From: Liu, Yi L yi.l.liu@intel.com Sent: Monday, November 27, 2023 2:39 PM
+static int vfio_pci_core_feature_pasid(struct vfio_device *device, u32
flags,
struct vfio_device_feature_pasid __user*arg,
size_t argsz)+{
- struct vfio_pci_core_device *vdev =
container_of(device, struct vfio_pci_core_device, vdev);- struct vfio_device_feature_pasid pasid = { 0 };
- struct pci_dev *pdev = vdev->pdev;
- u32 capabilities = 0;
- int ret;
- /* We do not support SET of the PASID capability */
this line alone is meaningless. Please explain the reason e.g. due to no PASID capability per VF...
sure. I think the major reason is we don't allow userspace to change the PASID configuration. is it?
if only PF it's still possible to develop a model allowing userspace to change.
but with VF this is not possible in concept.
- if (pdev->is_virtfn)
pdev = pci_physfn(pdev);- if (!pdev->pasid_enabled)
goto out;+#ifdef CONFIG_PCI_PASID
- pci_read_config_dword(pdev, pdev->pasid_cap + PCI_PASID_CAP,
&capabilities);+#endif
#ifdef is unnecessary. If CONFIG_PCI_PASID is false pdev->pasid_enabled won't be set anyway.
it's sad that the pdev->pasid_cap is defined under #if CONFIG_PCI_PASID. Perhaps we can have a wrapper for it.
oh I didn't note it.
and it should read from PCI_PASID_CTRL which indicates whether a capability is actually enabled.
yes, for the EXEC and PRIV capability, needs to check if it's enabled or not before reporting.
+/**
- Upon VFIO_DEVICE_FEATURE_GET, return the PASID capability for the
device.
- Zero width means no support for PASID.
also mention the encoding of this field according to PCIe spec.
yes.
or turn it to a plain number field.
It is not exact the same as the spec since bit0 is reserved. But here bit0 is used as well.
what is bit0 used for?